1. Field of the Invention
The present invention relates to the generation of three-dimensional images, and more particularly, to a system and methods for generating three-dimensional images from two-dimensional bioluminescence images and visualizing tumor shapes and locations.
2. Related Art
Bioluminescence imaging (BLI) is an emerging technique for sensitive and non-invasive imaging, which can be used for monitoring molecular events in living animals. Important applications of this imaging technique include gene therapy and cell trafficking studies. Unlike fluorescence-based optical imaging approaches which require an external source of light for excitation of fluorophores, BLI generates a two-dimensional (2D) view of gene expressions using a charge-coupled device (CCD) camera to detect the internal light produced by luciferases (catalysts in light generating reactions) through the oxidation of an enzyme-specific substrate (luciferin). The increasing use of BLI as a preferred modality for imaging small animals is due, in large part, to the need for repeatedly imaging animals that have been transplanted with gene-marked cells. Other imaging modalities, such as positron emission tomography (PET) and magnetic resonance imaging (MRI), are unsuitable for repeated and rapid imaging in laboratory settings.
Recent research activities have focused on bioluminescence tomography (BLT) in an effort to extract depth information from 2D bioluminescence images. Such efforts, however, have been largely ineffective in generating useful 3D images with high resolution. The use of multiple CCD cameras to measure bioluminescence signals has been suggested, but this approach is expensive and requires careful calibration of multiple cameras. As such, although BLI is a useful imaging modality for generating 2D images, there currently is no practical technique for rapidly generating three-dimensional (3D) images from a series of 2D BLI images.
In addition to the aforementioned limitations, existing BLI techniques do not allow for the rapid and accurate visualization of the physical shape and location of a tumor in a subject, in three dimensions. While there has been extensive research on multi-modal image registration in the image processing literature (based on matching geometric features or the optimization of intensity-based energy functions), no practical, 3D visualization approach for BLI images has been developed. Moreover, images generated by existing BLI techniques cannot be easily registered with 3D images generated by other imaging modalities (such as computed tomography (CT) and microCT) so that the physical shape and location of a tumor can be quickly discerned.
Accordingly, what would be desirable, but has not yet been provided, is a system and methods for generating three-dimensional images from two-dimensional, bioluminescence images and visualizing tumor shapes and locations.